Perhaps you should try some spelling variations:
quang dung » quang trung, ung dung, cuong dung
hanh tinh » hanh trinh, nhanh tinh, thanh tinh
trong dan » trong dang, trong san, trong tan
hoc hieu » hoc thieu, hoc hien, doc hieu
hieu cua » hieu qua, dieu cua, bieu cua
toan tai » toan tap, doanh tai, toan cao
toan ban » van ban

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: hoc hieu cua - hanh tinh quang dung trong dan ((toan tai) or (toan ban))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu cua - hanh tinh quang dung trong dan ((toan tai) OR (toan ban)).
• Adding a wildcard symbol may retrieve word variants: hoc hieu cua - hanh tinh quang dung trong dan ((toan tai) or (toan ban))*.